From 2a0d4c4d6ba5addb33cd1bccecc55ca4a095f191 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Wed, 2 Dec 2009 23:15:14 +0000
Subject: [PATCH] 2797.   [bug]           Don't decrement the dispatch
 manager's maxbuffers.                         [RT #20613]

---
 CHANGES            |  3 +++
 lib/dns/dispatch.c | 16 +++++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/CHANGES b/CHANGES
index 356ced04c1..2469aef5de 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+2797.	[bug]		Don't decrement the dispatch manager's maxbuffers.
+			[RT #20613]
+
 2796.	[bug]		Missing dns_rdataset_disassociate() call in
 			dns_nsec3_delnsec3sx(). [RT #20681]
 
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 9fa3500882..1d65ce43f4 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: dispatch.c,v 1.167 2009/11/25 23:49:21 tbox Exp $ */
+/* $Id: dispatch.c,v 1.168 2009/12/02 23:15:14 marka Exp $ */
 
 /*! \file */
 
@@ -2111,8 +2111,18 @@ dns_dispatchmgr_setudp(dns_dispatchmgr_t *mgr,
 
 	/* Create or adjust buffer pool */
 	if (mgr->bpool != NULL) {
-		isc_mempool_setmaxalloc(mgr->bpool, maxbuffers);
-		mgr->maxbuffers = maxbuffers;
+		/*
+		 * We only increase the maxbuffers to avoid accidental buffer
+		 * shortage.  Ideally we'd separate the manager-wide maximum
+		 * from per-dispatch limits and respect the latter within the
+		 * global limit.  But at this moment that's deemed to be
+		 * overkilling and isn't worth additional implementation
+		 * complexity.
+		 */
+		if (maxbuffers > mgr->maxbuffers) {
+			isc_mempool_setmaxalloc(mgr->bpool, maxbuffers);
+			mgr->maxbuffers = maxbuffers;
+		}
 	} else {
 		result = isc_mempool_create(mgr->mctx, buffersize, &mgr->bpool);
 		if (result != ISC_R_SUCCESS) {